1. Technical Field
This disclosure relates to digital radio communications systems, and more particularly, to circuitry for reconciling the time base embedded in a modulated signal to a time base of a digitizer in a receiver.
2. Description of the Related Art
Digital radio communications systems have become increasingly common in recent years. Two common forms of digital radio communications are the digital audio broadcast (DAB) system and HD (formerly Hybrid Digital) radio, both of which are used to transmit audio data. Digital radio communications systems that transmit video data are also becoming more commonplace.
In a digital radio communications system, source material is generated at a studio or other location and subsequently converted to a digital format. The resulting digital data may then be modulated. The conversion to digital and modulation of the source material may occur according to a first time base. As used herein, a definition of a time base may include the accuracy of the timekeeping provided by a particular clock or other timekeeping device. After modulation, the digitized source material may be conveyed to a transmitter, which in some cases is not co-located with the studio. The transmitter may upconvert the digitized, modulated source to a radio frequency (RF) signal that may then be transmitted over the airwaves. The transmission process may occur according to a second time base. The RF signal may be received at a receiver where it is subsequently downconverted to a baseband frequency and demodulated according to a third time base. The recovered source material may then be output through a speaker or provided to another device for further processing prior to playback.